Ultrasonic transmission and reflection measurements of a rat skull

An ultrasonic pulse-echo and transmission system was developed to enable measurements on rat skulls for the frequency range 0.5MHz to 10MHz. Experimental results showed that for frequencies below 2MHz transmission through the skull was high whilst above 5MHz the transmission is low and falling with increasing frequency; the reflected signal magnitude was comparatively constant. MicroCT imaging shows that the pores within the skull are of a size that in this frequency range would cause scattering of the propagating wave and the ultrasonic data does show the onset of an acoustic loss mechanism in the frequency range between 2MHz and 5MHz.